Hysteresis in Two Sands and the Independent Domain Model

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Abstract
Hysteresis in the relations between moisture content, potential, and conductivity was measured on two sands, one fine grained and the other coarse and angular grained. Hydraulic conductivity was determined during steady flow at selected capillary potentials. Water uptake and release from the samples was measured volumetrically at equilibrium points using multistep increments of capillary potential. Sets of primary draining and wetting scanning curves were obtained for both sands. Anomalies existed in the total water release and uptake for both main branch and scanning curves of the coarse sand. Considerable hysteresis occurred in the moisture content‐potential and conductivity‐potential relationships but little, if any, hysteresis was observed in the moisture content‐conductivity relationships. The independent domain theory of hysteresis predicted the scanning curves moderately well for the greater part of the hysteresis regions. Significant deviations were found in the high moisture content range in the fine grained sand.